1968, 4 years old by your post. It was fairly new then, the franchise we are all familiar with today. I never heard of them before. There were none in the northeast.
Wrong again, it was started as a franchise in 1952 with Sanders running it and was national in the 1960s, they were partners with the Big Boy franchise system in the nation Sander's sold it because it taxed him physically as well as fiscally, it stressed him. He sold it to Brown in exchange for lifetime employment security ie official company spokesperson.
KFC was featured in the James Bond film Goldfinger in 1964, filmed in 1963, it was well known by then...